I agree with the advice to eat more calories and carbs on workout days, with the carbs mostly after your workouts (the insulin will bring amino acids/glucose back into the muscle cells and aid recovery). Also people report having good success using , BCAA's or whey protein prior to workouts and L-glutamine after workouts. Creatine is another supplement that is documented to increase energy for lifting and to improve recovery. I haven't tried it yet but I plan to give it a go. I also agree with cutting back on the number of workouts per week to 3 or 4 rather than 5. That could prevent psychological as well as physical burn-out.
I'm a quitter...but I'm back now.